Stacking method of green sheet and a manufacturing method of multilayer ceramic electronic device

ABSTRACT

A method of stacking a green sheet, where, in rolling up a support sheet on which a multilayer unit including a green sheet and/or electrode layer is formed, the multilayer unit can be easily unrolled without adhering to the back surface of the support sheet, and in stacking the multilayer unit, the support sheet can be easily separated from the multilayer unit. On the surface  20   a  of the support sheet  20  is stacked a multilayer unit U 1  composed of an electrode layer  12   a  and/or green sheet  10   a  to form the support sheet with the laminated unit. Then, the support sheet  20  with the laminated unit is rolled up to form a rolled body R. The rolled body R is unrolled, the support sheet  20  with the multilayer unit is placed on a layer on which the support sheet is to be placed, the support sheet  20  is separated from the laminated unit U 1 , and the laminated unit U 1  is stacked. On the back surface  20   b  of the support sheet  20  is applied separation-facilitating surface treatment with a width equal to or greater than the width of the multilayer unit U 1,  and an adhereable portion  23  where the separation-facilitating surface treatment is not applied is also formed on the back face  20   b.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stacking method of green sheets andmanufacturing method of multilayer ceramic electronic device, andparticularly relates to a method such as to efficiently bond andtransfer electrode on a surface of dielectric green sheet or so.

2. Description of the Related Art

To manufacture multilayer ceramic electronic device such as multilayerceramic capacitor or so, ceramic paste made by ceramic powder, a binder(an acrylic based resin and a butyral resin, etc.), a plasticizer(phthalate ester, glycols, adipic acid, phosphate ester, etc.), and anorganic solvent (toluene, MEK, and acetone, etc.) are normally preparedfirst. Next, the ceramic paste is applied to a support sheet (PET, PP,etc.) by using the doctor blade method, etc., dried by heating, and PETfilm was released to obtain ceramic green sheet. Then, an internalelectrode was printed on the ceramic green sheet and dried, then aplurality of the results are stacked and cut to be a chip shape, so thata green chip is obtained. Then, after firing the green chip, an externalelectrode is formed, and electronic device such as multilayer ceramiccapacitor is manufactured.

However, in the case of printing the internal electrode paste on anextremely thin green sheet, there is a disadvantage that a bindercomponent in the green sheet is dissolved or swollen due to a solvent inthe internal electrode paste. Also, there is a disadvantage that aninternal electrode paste soaks in the green sheet. These disadvantagesmay cause a short-circuiting defect.

Therefore, a dry type electrode transferring method is proposed whereinforming an electrode on support sheet other than green sheet, then,bonding and transferring the same on the green sheet. Further, in orderto easily release electrode from the support sheet, a method whereinpreviously forming a release layer on a support sheet then, formingelectrode on the same is proposed. Also, in order to satisfactorily bondgreen sheet and electrode, a method, wherein previously bonding andtransferring a bond layer on the green sheet or the electrode, isproposed.

However, when a bond layer is continuously transferred on an electrodeor a green sheet and said layer is rolled up, due to an adhesiveness ofthe bond layer on the surface of electrode or green sheet, a problemthat the bond layer sticks to a back surface of support sheet may occur.Further, by providing a separation-facilitating surface treatment onboth surfaces of the support sheet, adhesiveness can be suppressed;however, this may cause difficulty to hold the support sheet whenreleasing the same. And this may also cause a slipping between a supportsheet and a roll, which is to move the support sheet, when the supportsheet is moving.

DISCLOSURE OF THE INVENTION

The present invention was made in consideration of the abovecircumstances and has an object thereof to provide a stacking method ofa green sheet, wherein in rolling up a support sheet on which multilayerunit comprising green sheet and/or electrode layer is formed, themultilayer unit can be easily unrolled without adhering to the backsurface of the support sheet, and in stacking the multilayer unit, thesupport sheet can be easily separated from the multilayer unit. Furtherobject of the present invention is to provide a method to easily andefficiently manufacture multilayer ceramic electronic device by usingthe stacking method of green sheet.

In order to achieve the abovementioned object, a stacking method ofgreen sheet according to the present invention comprises the steps of;

forming a support sheet with multilayer units by stacking the stakingunit that comprises electrode layer and/or green sheet on a surface ofthe support sheet,

forming a roll body by rolling up the support sheet with the multilayerunit, and

stacking the multilayer units by unrolling the roll body, placing thesupport sheet with multilayer unit on a layer which the support sheet isto be placed, and separating the support sheet from the multilayer unit,

wherein,

a separation-facilitating surface treatment with a width equal to orgreater than the width of the multilayer unit is formed on the backsurface of the support sheet and an adhesive part where theseparation-facilitating surface treatment is not provided is alsoformed.

Method of the present invention is particularly useful when stacking abond layer on a surface of the multilayer unit. Namely, in case formingan adhesive layer such as bond layer on a surface of multilayer unit,with the conventional method, a surface of the multilayer unit stick toa back surface of the support sheet when rolling up the support sheetforming multilayer unit. Accordingly, separation-facilitating surfacetreatment may be provided to the entire back surface of the supportsheet. However, with this conventional method, when stacking themultilayer unit, it becomes difficult to separate support sheet from themultilayer unit. The reason for this will be described below. Whenseparating support sheet from the multilayer unit, it is convenient toseparate the support sheet by sticking an adhesive tape on the backsurface of the support sheet. However, when a separation-facilitatingsurface treatment is provided on the back surface of support sheet, anadhesive tape does not adhere to the back surface of the support sheetand releasing the support sheet cannot efficiently be provided.

In the invention, due to adhesive parts existing at back surface ofsupport sheet, a device to help separating such as adhesive tape(adhesive sheet) can easily be fitted to the back surface. Accordingly,when separating support sheet from multilayer unit, adhesive tape isstuck to the back surface of support sheet and the support sheet caneasily be seaparated, and an attempt to efficiently stack the multilayerunit U1 can be made.

According to the method of the invention, a separation-facilitatingsurface treatment with a width equal to or greater than the width of themultilayer unit is provided. Accordingly, when rolling up the supportsheet with multilayer unit and forming a roll body, a surface ofmultilayer unit does not stick to back surface of support sheet.Accordingly, when unrolling the roll body, inconveniences such aslacking the outer surface layer of multilayer unit do not occur.Therefore, the method according to the invention can well stack(including transferring and bonding) the multilayer unit, andcontributes to making green sheets and/or electrode layers thin andincreasing a number of the stacking dielectric layer and/or internalelectrode layer.

Note that in the present invention, “a separation-facilitating surfacetreatment” is a surface treatment by which the multilayer unit is easilyseparated from the surface or back surface of the support sheet andsilicone treatment, alkyd resin treatment, and melamine resin treatmentor so is exemplified. Support sheet is not particularly limited, but PETor so is exemplified.

Preferably, the adhesive part is successively or intermittently formedalong a longitudinal direction of support sheet. The adhesive part is apart where a device to help separating, such as adhesive tape, isbonded. The adhesive part is preferably formed successively along alongitudinal direction of support sheet but can be formedintermittently.

Preferably, a part where a separation-facilitating surface treatment isprovided is successively formed along longitudinal direction on a backsurface of the support sheet. This is because, when support sheet withmultilayer unit is rolled up, a surface of multilayer unit continuouslyattach to a back surface of support sheet.

Preferably, the adhesive parts are formed on the back surface of supportsheet at one side or both sides of support sheet in the width direction.A device to help separating, such as adhesive tape, may bond to supportsheet even when adhesive part is only formed at one side of supportsheet in the width direction. However, in order to provide a dependablebonding, adhesive parts are preferable to be formed at both sides of thesupport sheet.

Preferably, a separation-facilitating surface treatment is provided onthe entire surface of the support sheet. Multilayer unit, which will beseparated later, is formed on the surface of the support sheet, and thata device to help separating, such as adhesive tape, is not required.Note, on the surface of support sheet, a separation-facilitating surfacetreatment with a width equal to that of the back surface, can beprovided, and an adhesive part can be provided at the remaining part.

Preferably, the roll body is unrolled, the support sheet with multilayerunit is cut, the support sheet with multilayer unit which is cut isplaced on a layer where it is to be stacked, the support sheet isseparated from the multilayer unit, and the multilayer unit is stacked.Multilayer unit may be stacked alone without cutting the support sheetwith multilayer unit which was unrolled from the roll body, however, itis easy to stack after cutting the support sheet with multilayer unit.

Preferably, the multilayer unit comprises an electrode layer havingpredetermined pattern and a blank pattern layer formed in a blank partbetween the electrode layers having predetermined patterns. In order toeliminate a level difference due to the electrode layer, it ispreferable to form blank pattern layer.

Manufacturing method of multilayer ceramic electronic device accordingto the present invention is characterized in that providing removingbinder treatment and firing the multilayer body which is stacked bygreen sheet stacking method as mentioned above. By manufacturingmultilayer ceramic electronic device using the stacking method of greensheet according to the present invention, making the dielectric layerand/or internal electrode layer thin, and increasing a number of thestacking dielectric layer and/or internal electrode layer can be easilyrealized.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of a multilayer ceramic capacitoraccording to a manufacturing method of an embodiment of the presentinvention;

FIG. 2(A) is a sectional view of a key part showing a manufacturingmethod of a multilayer ceramic capacitor as in FIG. 1, and FIG. 2(B) isa back view of a key part showing a support sheet as in FIG. 2(A);

FIG. 3 is a sectional view of a key part showing a continuation step ofFIG. 2(A);

FIG. 4 is a sectional view of a key part showing a continuation step ofFIG. 3;

FIG. 5 is a sectional view of a key part showing a continuation step ofFIG. 4;

FIG. 6 is a sectional view of a key part showing a continuation step ofFIG. 5;

FIG. 7 is a schematic view showing a rolling up step of a support sheetwith multilayer unit as in FIG. 6;

FIG. 8 is a sectional view of a key part showing a stacking state ofsupport sheet after rolled;

FIG. 9 is a schematic view showing a stacking method of a multilayerunit;

FIG. 10 is a schematic view showing a continuation step of FIG. 9;

FIG. 11 is a schematic view showing a continuation step of FIG. 10.

BEST MODE FOR CARRYING OUT THE INVENTION

First, as an embodiment of an electronic device manufactured by a methodaccording to the present invention, an overall configuration of amultilayer ceramic capacitor will be explained below.

As shown in FIG. 1, a multilayer ceramic capacitor 2 according to thepresent embodiment comprises a capacitor element 4, a first terminalelectrode 6 and a second terminal electrode 8. The capacitor element 4has dielectric layers 10 and internal electrode layers 12, and theinternal electrode layers 12 are alternately stacked between thedielectric layers 10. One side of the alternately stacked internalelectrode layers 12 is electrically connected to inside the firstterminal electrode 6 formed outside of a first end portion of thecapacitor element body 4. Also, the other side of the alternatelystacked internal electrode layers 12 is electrically connected to insideof the second terminal electrode 8 formed outside of a second endportion of the capacitor element body 4.

In the present embodiment, the internal electrode layer 12 is formed bytransferring an electrode layer 12 a to a ceramic green sheet 10 a asshown in FIG. 2 to FIG. 12, which will be explained later on.

A material of the dielectric layer 10 is not particularly limited andformed by a dielectric material, such as calcium titanate, strontiumtitanate and/or barium titanate. A thickness of each dielectric layer 10is not particularly limited but generally several μm to several hundredsof μ. Particularly, in the present embodiment, the layer is made thin aspreferably 5 μm or less and more preferably 3 μm or less.

Also, a material of the terminal electrodes 6 and 8 is not particularlylimited and normally copper, a copper alloy, nickel and nickel alloy,etc. are normally used and silver or silver alloy with palladium, etc.can be also used. Also, a thickness of the terminal electrodes 6 and 8is not particularly limited and is normally 10 to 50 μm or so.

A shape and size of the multilayer ceramic capacitor 2 may be suitablydetermined in accordance with the use object. When the multilayerceramic capacitor 2 is rectangular parallelepiped, it is normally alength (0.6 to 5.6 mm, preferably 0.6 to 3.2 mm)×width (0.3 to 5.0 mm,preferably 0.3 to 1.6 mm)×thickness (0.1 to 1.9 mm, preferably 0.3 to1.6 mm) or so.

Next, an example of a manufacturing method of the multilayer ceramiccapacitor 2 according to the present embodiment will be explained.

(1) First, a dielectric paste (paste for green sheet) is prepared toproduce a ceramic green sheet to compose the dielectric layer 10 shownin FIG. 1 after firing.

The dielectric paste is normally composed of an organic solvent basedpaste obtained by kneading a dielectric material (ceramic powder) withan organic vehicle.

The dielectric material may be suitably selected from a variety ofcompounds to be a composite oxide or oxide, such as carbonate, nitrate,hydroxide and organic metal compound, and mixed to be used. Thedielectric material is normally used as particles having an averageparticle diameter of 0.4 μm or less, preferably 0.1 to 3.0 μm or so.Note that it is preferable to use finer powder than a green sheetthickness to form an extremely thin green sheet.

The organic vehicle is obtained by dissolving a binder in an organicsolvent. The binder used for the organic vehicle is not particularlylimited and a variety of normal binders, such as ethyl cellulose,polyvinyl butyral, and an acrylic resin. Preferably, polyvinyl butyraland other butyral based resin are used.

Also, the organic solvent to be used for the organic vehicle is notparticularly limited and an organic solvent, such as terpineol, alcohol,butyl carbitol, acetone and toluene, is used.

Preferably, the binder is previously dissolved and filtered in analcohol solvent selected at least one kind or more from methanol,ethanol, propanol, and butanol to be a solution, and adding dielectricpowder and the other component in the solution. Binder having a highdegree of polymerization is difficult to dissolve in the solvent, andwith a general method, dispersion of paste tends to deteriorate.According to a method of the present embodiment, binder having a highdegree of polymerization is dissolved in the abovementioned feasiblesolvent to be a solution, then, ceramic powder and the other componentare added to the solution. Therefore, paste dispersion can be improvedand an occurrence of resin not dissolved in the solution can beprevented. By using solvents other than the abovementioned solvent, asolid condensation cannot be raised, and a change of lacquer viscosityover time tends to grow.

The dielectric paste may include additives selected from a variety ofdispersants, antistatic agents, plasticizers, dielectrics, glass flitsand insulators.

According to the present embodiment, it is not particularly limited butpreferably, nonionic dispersants of polyethylene glycols are used fordispersants, and shows 5 to 6 values of hydrophilic and lipophilicbalance (HLB). Dispersants are contained preferably by 0.5 to 1.5 partsby weight, and more preferably, 0.5 to 1.0 parts by weight, with respectto 100 parts by weight of ceramic powder.

According to the present embodiment, preferably dioctyl phthalate isused for plasticizer. Said dioctyl phthalate is contained by 40 to 70parts by weight, more preferably 40 to 60 parts by weight with respectto 100 parts by weight of binder. Compared to the other plasticizer,dioctyl phthalate is preferable for both sheet strength and sheetelongation, and particularly preferable for its small releasing strengthin order to easily release from a support sheet. Note when a content ofthe plasticizer is too small, sheet elongation tends to become small andflexuous characteristic tends to become small, while too large, theplasticizer bleeds out from the sheet and segregation of plasticizertoward said sheet is likely to occur and dispersion characteristic ofthe sheet tends to deteriorate.

Binder is preferably contained by 5 to 6.5 parts by weight with respectto 100 parts by weight of dielectric powder. When content of binder istoo small, sheet strength tends to deteriorate together with stackingability (bond strength when stacking), while too large, segregation ofbinder occurs and dispersant tends to deteriorate and sheet surfaceroughness tends to deteriorate.

It is preferable for the dielectric paste to include antistatic agentand said agent is an imidazoline based agent. The antistatic agent ispreferably contained by 0.1 to 0.75 part by weight, more preferably 0.25to 0.5 part by weight with respect to 100 parts by weight of ceramicpowder. When amounts of antistatic agent included are too small,antistatic efficiency become small, while too large, sheet surfaceroughness and also sheet strength tend to be deteriorated. Whenantistatic efficiency is too small, it may cause inconveniences suchthat static electricity is likely to occur when separating carrier sheet30 as support sheet from ceramic green sheet 10 a causing wrinkles onthe green sheet.

By using the dielectric paste, a green sheet 10 a is formed with athickness of preferably 0.5 to 30 μm, and more preferably 0.5 to 10 μmor so on a carrier sheet 30 as a second support sheet as shown in FIG. 4by the doctor blade method, etc. The green sheet 10 a is dried afterbeing formed on the carrier sheet 30. The drying temperature of thegreen sheet 10 a is preferably 50 to 100° C. and the drying time ispreferably 1 to 20 minutes. A thickness of the green sheet 10 a afterdrying is reduced to 5 to 25% of a thickness before drying. Thethickness of the green sheet 10 a after drying is preferably 3 μm orless.

(2) A carrier sheet 20 as a first support sheet is prepared separatelyfrom the above carrier sheet 30 as shown in FIG. 2A, a release layer 22is formed thereon, an electrode layer 12 a having a predeterminedpattern is formed thereon, and adjacent thereto, a blank pattern layer24 having substantially the same thickness as that of the electrodelayer 12 a is formed on a surface of the release layer 22 where theelectrode layer 12 a is not formed.

As carrier sheets 20 and 30, PET film or so is used and in order toimprove the easiness to separate said sheets from carrier sheets, it ispreferable to provide a separation-facilitating surface treatment.Thickness of these carrier sheets 20 and 30 are not particularly limitedbut preferably 5 to 100 μm. The thickness of these carrier sheets 20 and30 may be the same or different.

According to the present embodiment, as shown in FIG. 2(A), aseparation-facilitating surface treatment is provided on a surface 20 aof carrier sheet 20 as a first support sheet in order to improve theeasiness to separate. A part where a separation-facilitating surfacetreatment is provided is called “full treatment part 21 a”. Electrodelayer 12 a and blank pattern layer 24 are formed on the surface of saidfull treatment part 21 a. Note that a part where electrode layer 12 a isnot formed is determined to be back surface 20 b of career sheet 20.

As a separation-facilitating surface treatment, methods of coatingsilicone, alkyd resin, or melamine resin on the surface of carrier sheet20 are exemplified. “Partial treatment part 21 b” where aseparation-facilitating surface treatment is partially provided, and“adhesive part 23” where a separation-facilitating surface treatment isnot provided, are formed on back surface 20 b of carrier sheet 20. Awidth W1 of partial treatment part 21 b shown in FIG. 2(B) with a widthequal to or greater than the width of the electrode layer 12 a and blankpattern layer 24, on the other, less than a width W of carrier sheet.And adhesive parts 23 where a separation-facilitating surface treatmentis not provided are formed on both sides of partial treatment part 21 b.

Width W2 of adhesive parts is preferably 3 to 30 mm, more preferably 5to 10 mm. Note that, in the invention, one side of adhesive part 23 maynot be formed. In the embodiment, full treatment part 21 a and partialtreatment part 21 b are successively formed along a longitudinaldirection X of carrier sheet 20. Further, adhesive parts 23 are alsosuccessively formed along a longitudinal direction X of carrier sheet20.

The release layer 22 formed on a surface 21 a of career sheet 20preferably includes the same dielectric particles as that in thedielectrics composing the green sheet 10 a shown in FIG. 4. Also, therelease layer 22 includes a binder, plasticizer and release agent otherthan the dielectric particles. A particle diameter of the dielectricparticles may be the same as that of the dielectric particles includedin the green sheet, but is preferably smaller.

In the present embodiment, a thickness of the release layer 22 ispreferably thinner than a thickness of the electrode layer 12 a and isset to have a thickness of preferably 60% or less, and more preferably30% or less with respect to a thickness of electrode layer.

A coating method of the release layer 22 is not particularly limited butthe coating method using a wire bar coater or a die coater or so ispreferable since it is necessary to make the coating extremely thin.Note that adjustment of the thickness of the release layer can be madeby selecting a wire bar coater-having a different wire diameter. Namely,to make the thickness of the applying release layer thin, a smaller wirediameter can be selected, while to make it thick, larger wire diametercan be selected. The release layer 22 is dried after being applied. Thedrying temperature is preferably 50 to 100° C. and the drying time ispreferably 1 to 10 minutes.

A binder for the release layer 22 is composed, for example, of anacrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol,polyolefin, polyurethane, polystyrene, or an organic composed of acopolymer of these or emulsion. Plasticizers contained in the releaselayer 22 and in the green sheet 10 a may be the same or different,however, they are preferably the same.

A plasticizer for the release layer 22 is not particularly limited and,for example, phthalate ester, phthalate dioctyl, adipic acid, phosphateester and glycols, etc. may be mentioned. Plasticizers contained in therelease layer 22 and in the green sheet 10 a may be the same ordifferent, however, they are preferably the same.

A release agent for the release layer 22 is not particularly limitedand, for example, paraffin, wax and silicone oil, etc. may be mentioned.A release agent contained in the release layer 22 may be the same asthat contained in the green sheet 10 a or may be different from that.

A binder is contained in the release layer 22 by preferably 2.5 to 200parts by weight, more preferably 5 to 30 parts by weight, andparticularly preferably 8 to 30 parts by weight or so with respect to100 parts by weight of dielectric particle.

A plasticizer is preferably contained in the release layer 22 by 0 to200 parts by weight, preferably 20 to 200 parts by weight, and morepreferably 50 to 100 parts by weight with respect to 100 parts by weightof the binder. Note that a content ratio of the plasticizer.

A release agent is preferably contained in the release layer 22 by 0 to100 parts by weight, preferably 2 to 50 parts by weight, and morepreferably 5 to 20 parts by weight with respect to 100 parts by weightof the binder.

After forming the release layer 22 on the surface of the carrier sheet20, as shown in FIG. 2(A), an electrode layer 12 a to compose aninternal electrode layer 12 after firing is formed to be a predeterminedpattern on the surface of the release layer 22. A thickness of theelectrode layer 12 a is preferably 0.1 to 2 μm, and more preferably 0.1to 1.0 μm or so. The electrode layer 12 a may be configured by a singlelayer or two or more layers having different compositions.

The electrode layer 12 a can be formed on the surface of the releaselayer 22 by a thick film formation method, such as a printing methodusing an electrode paste, or a thin film method, such as evaporation andsputtering. When forming the electrode layer 12 a on the surface of therelease layer 22 by a screen printing method or a gravure printingmethod as a kind of thick film method, it is as follows.

First, an electrode paste is prepared. The electrode paste is fabricatedby kneading a conductive material composed of a variety of conductivemetals and alloys, or a variety of oxides, organic metal compounds orresinates, etc. to be conductive materials after firing, with an organicvehicle.

As a conductive material to be used when producing the electrode paste,Ni, a Ni alloy and a mixture of these are used. A shape of theconductive materials is not particularly limited and may be a sphericalshape and scale-like shape, etc. or a mixture of these shapes. Thosehaving an average particle diameter of the conductive material ofnormally 0.1 to 2 μm, and preferably 0.2 to 1 μm or so may be used.

An organic vehicle contains a binder and a solvent. As the binder, forexample, ethyl cellulose, an acrylic resin, polyvinyl butyral, polyvinylacetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, or acopolymer of these may be mentioned. Particularly, butyrals, such aspolyvinyl butyral, are preferable.

The binder is contained in the electrode paste by preferably 8 to 20parts by weight with respect to 100 parts by weight of the conductivematerial (metal powder). As a solvent, any of well-known ones, such asterpineol, butylcarbitol and kerosene, may be used. A content of thesolvent is preferably 20 to 55 wt % or so with respect to the entirepaste.

To improve the adhesiveness, the electrode paste preferably contains aplasticizer. As a plasticizer, benzylbutyl phthalate (BBP) and otherphthalate esters, adipic acids, phosphoric esters, and glycols, etc. maybe mentioned. The plasticizer in the electrode paste is preferably 10 to300 parts by weight, and more preferably 10 to 200 parts by weight withrespect to 100 parts by weight of the binder. Note that when an addingquantity of the plasticizer or adhesive is too large, it is liable thatstrength of the electrode layer 12 a remarkably declines. Also, toimprove transferability of the electrode layer 12 a, it is preferable toimprove adhesiveness and/or adherence of the electrode paste by adding aplasticizer and/or adhesive to the electrode paste.

After or before forming the electrode paste layer having a predeterminedpattern on the surface of the release layer 22 by a printing method, ablank pattern layer 24 is formed to be substantially the same thicknessas that of the electrode layer 12 a on the surface of the release layer22 not formed with the electrode layer 12 a. The blank pattern layer 24is composed of the same material as that of the green sheet 10 a shownin FIG. 4 and formed by the same method. The electrode layer 12 a andthe blank pattern layer 24 are dried in accordance with need. The dryingtemperature is not particularly limited, but is preferably 70 to 120°C., and the drying time is preferably 5 to 15 minutes.

(3) As shown in FIG. 2A, an adhesive layer transfer sheet formed with anadhesive layer 28 is prepared on the surface of a carrier sheet 26 as athird support sheet separately from the carrier sheets 20 and 30explained above. The carrier sheet 26 is formed by the same sheet asthat of the carrier sheets 20 and 30.

A composition of the adhesive layer 28 is the same as that of therelease layer 22 except for not containing a release agent. Namely, theadhesive layer 28 contains a binder, a plasticizer and a release agent.The adhesive layer 28 may contain the same dielectric particle as thatof the dielectrics composing the green sheet 10 a, however, in the caseof forming an adhesive layer having a thinner thickness than a particlediameter of the dielectric particles, it is better not to containdielectric particles. Also, when dielectric particles are contained inthe adhesive layer 28, a particle diameter of the dielectric particlesis preferably smaller than the particle diameter of the dielectricparticles contained in the green sheet.

A plasticizer is preferably contained in the adhesive layer 28 by 0 to200 parts by weight, preferably 20 to 200 parts by weight, and morepreferably 50 to 100 parts by weight with respect to 100 parts by weightof the binder.

The adhesive layer 28 further contains an antistatic agent, and theantistatic agent includes one of imidazoline based surfactants, and aweight based adding quantity of the antistatic agent is preferably notlarger than that of the binder (organic polymer material). Namely, theantistatic agent is preferably contained in the adhesive layer 28 by 0to 200 parts by weight, preferably 20 to 200 parts by weight, and morepreferably 50 to 100 parts by weight with respect to 100 parts by weightof the binder.

A thickness of the adhesive layer 28 is preferably 0.02 to 0.3 μm or so,more preferably, thinner than an average particle diameter of dielectricparticles contained in the green sheet. Further, a thickness of theadhesive layer 28 is preferably 1/10 or less of a thickness of the greensheet 10 a l or thinner.

When a thickness of the adhesive layer 28 is too thin, the adhesiveforce declines, while when too thick, spaces are easily formed inside anelement body after sintering depending on the thickness of the adhesivelayer, and a capacitance by an amount of the volume tends to decreaseremarkably.

The adhesive layer 28 is formed on the surface of the carrier sheet 26as a third support sheet, for example, by a bar coater method, diecoater method, reverse coater method, dip coater method and kiss coatermethod, etc. and dried in accordance with need. The drying temperatureis not particularly limited, but is preferably the room temperature to80° C., and the drying time is preferably 1 to 5 minutes.

(4) To form the adhesive layer on the surface of the electrode layer 12a and the blank pattern layer 24 shown in FIG. 2(A), a transfer methodis applied in the present embodiment. Namely, as shown in FIG. 3, theadhesive layer 28 of the carrier sheet 26 is pressed against the surfaceof the electrode layer 12 a and the blank pattern layer 24, heated andpressed, then, the carrier sheet 26 is removed. Consequently, theadhesive layer 28 is transferred to the surface-of the electrode layer12 a and the blank pattern layer 24. Note that transfer of the adhesivelayer 28 may be performed on the surface of the green sheet 10 a shownin FIG. 4.

The heating temperature at transferring is preferably 40 to 100° C., andthe pressing force is preferably 0.2 to 15 MPa. Pressing may beperformed by a press or a calendar roll, but is preferably performed bya pair of rolls.

After that, the green sheet 10 a formed on the surface of the carriersheet 30 shown in FIG. 4 is transferred on the electrode layer 12 a andthe blank pattern layer 24 via the adhesive layer 28. Heating andpressing at the time of transferring may be pressing and heating by apress or by a calendar roll, but is preferably performed by a pair ofrolls. The heating temperature and the pressing force are same as thoseat the time of transferring the adhesive layer 28.

As shown in FIG. 5, the adhesive layer 28 is transferred to the surfaceof the green sheet 10 a. The transfer is the same with that of bondlayer 28 as shown in FIG. 3. Next, as shown in FIG. 6, the carrier sheet20 with multilayer unit wherein a multilayer unit U1 is formed can beobtained by separating the support sheet 26. The multilayer unit U1 is a5 layered multilayer structure comprising bond layer on the outersurface of the unit and green sheet 10 a and electrode layer 12 a insidethe unit.

Carrier sheet 20 where multilayer unit U1 is formed on the surfacebecomes roll body R as shown in FIG. 7. Said roll body R is easy toconvey and store. Carrier sheet 20 with multilayer unit, which is rolledby the roll body R is stacked as shown in FIG. 8.

Namely, as shown in FIG. 8, a bond layer 28, placed at the top ofmultilayer unit U1 which is formed on a surface of carrier sheet 20,contacts a partial treatment part 21 b, which is formed on a backsurface 20 b of carrier sheet 20 located at the top of said bond layer28, and does not contact adhesive part 23. A partial treatment part 21 bis a part where separation-facilitating surface treatment is providedand does not bond to a bond layer 28 even when they are in contact.

As shown in FIG. 7, carrier sheet 20 with multilayer unit can easily beunrolled from the roll R. Moreover, even when carrier sheet 20 withmultilayer unit is unrolled, a part of multilayer unit U1 including bondlayer 28 will not be adhesive to back surface of the carrier sheet 20.

(5) After the conveyance or the storage of the roll R, carrier sheet 20with multilayer unit was unrolled and if necessary, the sheet 20 was cutin the required length and stacks the multilayer unit U1 bytransferring. Concretely, first, as shown in FIG. 9, carrier sheet onwhich an exterior green sheet (a thick multilayer wherein a pluralnumber of green sheet without forming an electrode is fixed) 40 isformed is fixed on lower configuration 50. Then, multilayer units U1 arerespectively stacked on exterior green sheet 40.

When stacking the multilayer unit U1, a back surface 20 b of carriersheet 20 forming multilayer unit U1 on its surface is made to faceupward, and bond layer 28 of multilayer unit U1 is pressed against uppersurface of green sheet 40. In order to add pressure to carrier sheet 20,upper configuration 52 can be used and the upper configuration 52 can bepressed against lower configuration 50 by contacting back surface 20 bof the carrier sheet 20.

Then, as shown in FIG. 10, upper configuration 52 can be released andadhesive tape (adhesive sheet) 70 sticks to back surface 20 b of carriersheet 20, which is to help separating. On the back surface 20 b ofcarrier sheet 20, adhesive part 23 where a separation-facilitatingsurface treatment is not provided exists and adhesive tape 70conveniently sticks to back surface of carrier sheet 20.

Then, by turning adhesive tape 70 over to upper side, carrier sheet 20will also be turned up together with the adhesive tape 70, and as shownin FIG. 11, the carrier sheet 20 will be released from the multilayerunit U1. By repeating the abovementioned steps as shown in FIGS. 9 to11, a plural number of multilayer units U1 can be stacked on theexterior green sheet 40. Stacking a plural number of multilayer unitsU1, forming green sheets 10 a and electrode layers 12 a with a requirednumber of layers, exterior green sheet 40 is stacked on the top, then,the final pressing is done.

Pressure at the time of the final pressing is preferably 10 to 200 MPa.The heating temperature is preferably 40 to 100° C. After that, themultilayer body is cut to be a predetermined size to form green chips.The green chips are subjected to binder removal process and firingprocess, then, thermal treatment is performed in order to re-oxidize thedielectric layer.

The binder removal processing may be performed under a normal condition,but when using a base metal, such as Ni and a Ni alloy as a conductivematerial of the internal electrode layer, it is preferably performedunder the specific condition below.

temperature rising rate: 5 to 300° C./hour, particularly 10 to 50°C./hour

holding temperature: 200 to 400° C., particularly 250 to 350° C.

holding time: 0.5 to 20 hours, particularly 1 to 10 hours

atmosphere: a wet mixed gas of N₂ and H₂

A firing condition is preferably as below.

temperature rising rate: 50 to 500° C./hour, particularly 200 to 300°C./hour

holding temperature: 1100 to 1300° C., particularly 1150 to 1250° C.

holding time: 0.5 to 8 hours, particularly 1 to 3 hours

cooling rate: 50 to 500° C./hour, particularly 200 to 300° C./hour

atmosphere gas: a wet mixed gas of N₂ and H₂, etc.

Note that oxygen partial pressure in an atmosphere in the air at firingis preferably 10⁻² Pa or lower, particularly 10⁻² to 10⁻⁸ Pa. Whenexceeding the above ranges, the internal electrode layer tends tooxidize, while when the oxygen partial pressure is too low, abnormalsintering is caused in an electrode material of the internal electrodelayer to be broken.

The thermal treatment after performing such firing is preferablyperformed with a holding temperature or highest temperature of 1000° C.or higher, more preferably 1000 to 1100° C. When the holding temperatureor the highest temperature at the time of the thermal treatment is lowerthan the above ranges, it is liable that oxidization of the dielectricmaterial is insufficient to make the insulation resistance lifetimeshort, while when exceeding the above ranges, Ni in the internalelectrode oxidizes and the capacity decreases, moreover, Ni reacts witha dielectric base and the lifetime also tends to become short. Theoxygen partial pressure at the time of thermal treatment is higher thanthat in-a reducing atmosphere at the time of firing, preferably 10⁻³ Pato 1 Pa, and more preferably 10⁻² Pa to 1 Pa. When it is lower than theabove range, re-oxidization of the dielectric layer 2 becomes difficult,while when exceeding the above ranges, the internal electrode layer 3tends to oxidize. Other condition of the thermal treatment is preferablyas below.

holding time: 0 to 6 hours, particularly 2 to 5 hours

cooling rate: 50 to 500° C./hour, particularly 100 to 300° C./hour

atmosphere gas: wet N₂ gas, etc.

Note that to wet a N₂ gas or a mixed gas, etc., for example, a wetter,etc. may be used. In this case, the water temperature is preferably 0 to75° C. or so. Also, the binder removal processing, firing and thermaltreatment may be performed continuously or separately. When performingcontinuously, the atmosphere is changed without cooling after the binderremoval processing, continuously, the temperature is raised to theholding temperature at firing to perform firing. Next, it is cooled andthe thermal treatment is preferably performed by changing the atmospherewhen the temperature reaches to the holding temperature of the thermaltreatment. On the other hand, when performing them separately, afterraising the temperature to the holding temperature at the binder removalprocessing in an atmosphere of a N₂ gas or a wet N₂ gas, the atmosphereis changed, and the temperature is furthermore raised. After that, aftercooling the temperature to the holding temperature at the thermaltreatment, it is preferable that the cooling continues by changing theatmosphere again to a N₂ gas or a wet N₂ gas. Also, in the thermaltreatment, after raising the temperature to the holding temperatureunder the N₂ gas atmosphere, the atmosphere may be changed, or theentire process of the thermal processing may be in a wet N₂ gasatmosphere.

The thus obtained sintered body (element body 4) is subjected to endsurface polishing, for example, by barrel polishing and sand-blast,etc., then, a terminal electrode paste is burnt to form terminalelectrodes 6 and 8. For example, a firing condition of the terminalelectrode paste is preferably in a wet mixed gas of N₂ and H₂ at 600 to800° C. for 10 minutes to 1 hour or so. In accordance with need,plating, etc. is performed on the terminal electrodes 6 and 8 to form apad layer. Note that the terminal electrode paste may-be fabricated inthe same way as the electrode paste explained above.

A multilayer ceramic capacitor of the present invention produced asabove is mounted on a print substrate, etc. by soldering, etc. and usedfor a variety of electronic equipments, etc.

In a method of manufacturing a multilayer ceramic capacitor according tothe present embodiment, it is possible to easily transfer a dry typeelectrode layer 12 a to a surface of the green sheet 10 a with highaccuracy without breaking or deforming the green sheet 10 a.

Particularly, in the manufacturing method of the present embodiment, theadhesive layer 28 is formed on the surface of the electrode layer orgreen sheet by the transfer method, and the electrode layer 12 a isbonded with the surface of the green sheet 10 a via the adhesive layer28. By forming the adhesive layer 28, a high pressure and heat becomeunnecessary at the time of bonding the electrode layer 12 a to transferto the surface of the green sheet 10 a, so that bonding at a lowerpressure and lower temperature becomes possible. Accordingly, even inthe case of an extremely thin green sheet 10 a, the green sheet 10 a isnot-broken, the electrode layers 12 a and green sheets 10 a can bepreferably stacked, and short-circuiting defect, etc. are not caused.

Furthermore, in the present embodiment, the adhesive layer 28 is notdirectly formed on a surface of the electrode layer 12 a or green sheet10 a by a coating method, etc. and formed by a transfer method, so thatcomponents of the adhesive layer 28 do not soak in the electrode layer12 a or green sheet 10 a, and it becomes possible to form an extremelythin adhesive layer 28. For example, a thickness of the adhesive layer28 can be made thin as 0.02 to 0.3 μm or so. Although the thickness ofthe adhesive layer 28 is thin, components of the adhesive layer 28 donot soak in the electrode layer 12 a and green sheet 10 a, the adhesiveforce is sufficient and a composition of the electrode layer 12 a orgreen sheet 10 a is not adversely affected.

Particularly, according to the present embodiment, due to adhesive parts23 existing at back surface 20 b of carrier sheet 20 as support sheet, adevice to help separating such as adhesive tape (adhesive sheet) 70 caneasily be fitted to the back surface 20 b as shown in FIG. 10.Accordingly, when separating carrier sheet 20 from multilayer unit U1,adhesive tape 70 is stuck to the back surface 20 b of carrier sheet 20and the carrier sheet 20 can easily be separated, and an attempt toefficiently stack (including the transferring and bonding) themultilayer unit U1 can be made.

Further, according to the present embodiment, on the back surface 20 bof carrier sheet 20, as shown in FIG. 8, a separation-facilitatingsurface with a width equal to or greater than the width of themultilayer unit U1 is provided. Accordingly, when rolling up the carriersheet 20 with multilayer unit, and even when forming a roll body R, bondlayer 28 which is a surface of multilayer unit U1, does not stick toback surface 20 b of carrier sheet 20. Accordingly, when unrolling theroll body R, inconveniences such as lacking the outer surface layer ofmultilayer unit U1 do not occur. Therefore, multilayer unit U1 can bewell stacked (including transferring and bonding) and contribute tomaking green sheets and/or electrode layers thin and increasing a numberof the stacking dielectric layer and/or internal electrode layer.

Note that the present invention is not limited to the above embodimentsand may be variously modified within the scope of the present invention.

For instance, a method of the present invention is not limited to amanufacturing method of multilayer ceramic capacitor, but can be appliedto manufacturing method of the other multilayer electronic devices.

Further, according to the embodiment mentioned above, as shown in FIGS.6 and 7, multilayer unit U1 formed on the surface of carrier sheet 20comprises 5 layers, however, in the invention, said multilayer unit U1is not limited to the 5 layers and can be any number of layers. Further,multilayer unit U1 formed on the surface of carrier sheet 20, may be asingle layer of green sheet 10 a, a single layer of inner electrode 12a, a single layer of bond layer 28, or combinations thereof.

As described above, according to the present invention, when rolling upthe support sheet, where multilayer unit comprising green sheet and/orelectrode is formed, the multilayer unit does not stick to a backsurface of the carrier sheet and can easily be unrolled. Moreover, whenstacking multilayer unit, support sheet can easily separated frommultilayer unit.

1. A stacking method of green sheet comprising the steps of; forming asupport sheet with multilayer units by stacking the multilayer unit thatcomprises electrode layer and/or green sheet on a surface of the supportsheet, forming a roll body by rolling up the support sheet with themultilayer unit, and stacking the multilayer units by unrolling the rollbody, placing the support sheet with multilayer unit on a layer whichthe support sheet is to be placed, and separating the support sheet fromthe multilayer unit, wherein, a separation-facilitating surfacetreatment with a width equal to or greater than the width of themultilayer unit is formed on the back surface of the support sheet andan adhesive part where the separation-facilitating surface treatment isnot provided is also formed.
 2. The stacking method of green sheet asset forth in claim 1, wherein the adhesive part is successively orintermittently formed along a longitudinal direction of the supportsheet on the back surface of said support sheet.
 3. The stacking methodof green sheet as set forth in claim 1, wherein a part where theseparation-facilitating surface treatment is provided is successivelyformed along a longitudinal direction of the support sheet on the backsurface of said support sheet.
 4. The stacking method of green sheet asset forth in claim 1, wherein the adhesive parts are formed on the backsurface of support sheet on one side or both sides of a width directionof said support sheet.
 5. The stacking method of green sheet as setforth in claim 1, wherein on a surface of the support sheet, theseparation-facilitating surface treatment, having a width equal to orgreater than a width of the separation-facilitating surface treatmentprovided on the back surface of the support sheet.
 6. The stackingmethod of green sheet as set forth in claim 1, wherein bond layer isstacked on a surface of the multilayer unit.
 7. The stacking method ofgreen sheet as set forth in claim 1, wherein an adhesive sheet isadhered to a back surface of support sheet, and by using said adhesivesheet, said support sheet is separated from the multilayer unit.
 8. Thestacking method of green sheet as set forth in claim 1, wherein the rollbody is unrolled, the support sheet with multilayer unit is cut, the cutsupport sheet with multilayer unit is placed on a layer where it is tobe stacked, the support sheet is separated from the multilayer unit, andthe multilayer unit is stacked.
 9. The stacking method of green sheet asset forth in claim 1, wherein the multilayer unit comprises an electrodelayer having a predetermined pattern and a blank pattern layer formed ina blank part between the electrode layers having a predeterminedpattern.
 10. A method of manufacturing a multilayer ceramic electronicdevice, comprising the steps of providing removing binder treatment andfiring a multilayer body which is stacked by green sheet stacking methodas set forth in claim 1.